Ecosystem Studies
ofSubarctic and Arctic Seas
(ESSAS)
Annual Science Meeting 2021
Book of Abstract
Online30 May – 3 June 2021

Table of Contents
Conference Call1

Welcome2

Meeting Schedule & Programme

3

Abstract of Presentation8

1

Welcome to ESSAS Annual
Science Meeting 2021

Prof. Toru Hirawake (Local Organizer)
Dr. Naomi Harada (Co-Chair)
National Institute ofJapan Agency for
Polar Research
Marine-Earth Science and Technology

ESSAS Co-Chair and Local Organizing Committee would
like to welcome you to the ESSAS Annual Science Meeting2021. While we need to hold the meeting online due tothe COVID pandemic persisting since its outbreak in 2019,
we believe that you will still hear at ESSAS 2021 the bestof what our colleagues has produced in a spectrum ofscientific topics relevant to the subarctic and arctic seas,and even more.
We think that it is particularly important to share ourscientific knowledge with not only scientific communities
but also with the general public. Hence, ESSAS ASM 2021
includes both a public lecture and a stakeholder meetingfor the first time in the ESSAS ASM history. We hope thatyou enjoy all aspects of ESSAS ASM 2021!
Co-chair and Local Organizing Committee**Naomi Harada (JAMSTEC), Toru Hirawake(NIPR),
Sei-Ichi saitoh (Hokkaido Univ.), Mitsutaku Makino(The Univ. of Tokyo), Taka Hirata (Hokkaido Univ.)2

Schedule
A.M.

P.M.

(Zoom URLs, different each day, are provided to registered participants
only a few days before the actual meeting dates for security reasons)

30 May（Sun）

31 May（Mon）

1 June（Tue）

2 June（Wed）-

Plenary
Talks

ResearchPresentations

AnaloguART- PESAS Joint
Workshop

Stake
HolderMeeting

ResearchPresentations

AnaloguART- PESAS Joint
WorkshopOpen
Lecture(Live)(18-19:00)

3 June（Thu）
Science
Steering
Committee
Meeting-

Scientific Programme【Day 1: 30 May (Sun)】 (Time in Japan Standard Time, JST)
18:00-19:00 (Live)
Open Lecture “Mammals in the sea”
Yoko Mitani (Field Science Center for Northern Biosphere, Hokkaido
University)【Day 2: 31 May (Mon)】 (Time in Japan Standard Time, JST)
09:00-09:05 Welcome Greetings
Yasushi Fukamachi (Arctic Research Center, Hokkaido University)
09:10-9:35 Plenary Talk 1“A song of spring and a story of winds: The relationship among Pacificherring (Clupea pallasii) , winds, sea, ice and people from the past
to the future” by Naoki Tojo (Faculty of Fisheries Sciences, Hokkaido
University)
09:35-10:00 Plenary Talk 2“Assessing and managing fish stocks in a rapidly changing
environment” by Franz Mueter (College of Fisheries and Ocean
Sciences, University of Alaska Fair Banks)
10:00-10:25 Plenary Talk 3“Reframing the interface of science, policy and industry for the
better ecosystem governance in the Anthropocene” by Aoi
Sugimoto (Japan Fisheries Research and Education Agency)3

【Day 2: 31 May (Mon) (cont.)】 (Time in Japan Standard Time, JST)
Stake Holder Meeting
13:00-15:00 ・Self-introduction of participants
・Knowledge transfer among participants
・Discussion towards co-designing of future fisheries andmarine science【Day 3: 1 June (Tue)】 (Time in Japan Standard Time, JST)
05:00-05:15 Possible future scenarios for Arctic Gateways connecting
Subarctic and Arctic marine systems: I. Climate and physicalchemical oceanography (Ken Drinkwater)
05:15-05:30 Capital investments for the Norwegian Red King Crab: A
Tale of Ecological and Community Resilience (Melina
Kourantidou / Brooks Kaiser)
05:30-05:45 Identifying ecosystem reference states with “Chance andNecessity” model simulations (Elliot Sivel)
05:45-06:00 Arctic marine biogeochemical modeling in the ArCSII
Project (Eiji Watanabe)
06:00-:6:15 Highlights of the R/V Mirai Arctic Ocean survey in 2020
(Shigeto Nishino)
06:15-06:35 Break
06:35-06:50 Inter-annual variability of phytoplankton community
structure in the Pacific Arctic Region (Amane Fujiwara)
06:50-07:05 Impact of sea-ice dynamics on the spatial distribution of
diatom resting stages in sediments of the Pacific-Arctic
Ocean (Yuri Fukai)
07:05-07:20 Increasing zooplankton biomass associated with sea ice loss
in the western Arctic Ocean and its ecological impacts(Motoyo Itoh)
07:20-7:35 Inter-annual changes of the mesozooplankton community
structure in the Western Arctic Ocean during summers of
2015-2018 (Jee-Hoon Kim)
07:35-07:50 Response of zooplankton community with early sea-ice
reduction in the northern Bering Sea during summers 2017,2018 (Kohei Matsuno)
07:50-15:00 Break4

【Day 3: 1 June (Tue) (cont.)】 (Time in Japan Standard Time, JST)
15:00-15:15 Comparison of population structure, vertical distribution,and growth of the sympatric, carnivorous, mesopelagic
copepods Paraeuchaeta glacialis and Heterorhabdus
norvegicus in the western Arctic Ocean: Occurrence of rstrategy mesopelagic copepods may be related to their
specialized feeding mode (Atsushi Yamaguchi)
15:15-15:30 Distribution and shell condition of Limacina helicina inaragonite undersaturated waters of the Canada Basin(Michiyo Yamamoto-Kawai)
15:30-15:45 Impacts of riverine carbon and nutrient delivery on Arctic
Ocean acidification (Yuanxin Zhang)
15:45-16:00 Underwater soundscape and its temporal variability in the
East Siberian Sea (Dong-Gyun Han)
16:00-16:15 Arctic Ocean CO2uptake (Sayaka Yasunaka
16:15-16:35 Break
16:35-16:50 Changes and future predictions of Oyashio Intermediate
Water, a key water mass for biological production (Vigan
Mensah)16:50-17:05 Marine Ecosystem Variations over the North Pacific andtheir Linkage to Large-Scale Climate Variability and Change(Shoshiro Minobe)
17:05-17:20 Optimization of salmon release operation under changing
climate in the Okhotsk coast, Japan (Sei-Ichi Saitoh)
17:20-17:35 Two species of seabirds used contrasting marine habitat
across the cold water belt along the coast of northern
Hokkaido in the southwestern Okhotsk Sea (Bungo
Nishizawa)
17:35-17:50 Foraging behavior and prey field of Short-tailed
Shearwaters using northern North Pacific and Southern
Ocean (Yutaka Watanuki)

5【Day 4: 2 June (Wed)】 (Time in Japan Standard Time, JST)
06:00 - 8:00 AnalogueART – PESAS Joint Workshop (First Session)・Advantages and challenges of using environmental gradients andmosaics as analogues of future climate change (Samuel Rastrick,
Kumiko Azetsu-Scott, Melissa Chierici)
・Introduction to PESAS and the use of paleo-proxies to understandlong-term dynamics and frame future scenarios (Ben Fitzhugh)・[Title To be announced] (Ben Gaglioti)
・It’s in their bones” (Paleoecology hacks for the uninitiated)(Nicole Misarti)
・Using environmental mosaics to understand the future of Norwegiancoral reefs (Tina Kutti)
・Using environmental mosaics in modal parametrisation and validation(Antonio Aguera Garcia)
・[Title To Be Announced] (Laura Gemery)
・[Title To Be Announced] (Catherine West)・(To Be Determined) (Christine Bassett)
Poster Introduction:
09:00 - 09:02 Zooplankton biomass and biodiversity on the Sofala Bank
(Ceiça Chioze)
09:02 - 09:04 Climate change adaptation in aquaculture: A systematic
review (Eranga Galappaththi)
09:04 - 09:06 Impacts of meltwater discharge from marine-terminating
glaciers on the protist community in Inglefield Bredning,northwestern Greenland (Kohei Matsuno)
09:06 - 09:08 Studies on Limacina helicina at Mombetsu in thesouthern Okhotsk Sea (Kohei Matsuno)
09:10 - 09:12 Understanding the Current Status of Seawater pH
Changes Near Scallop Aquaculture Facilities in Northern
Japan (Ayumi Mori)
09:12 - 09:14 Social, economic, and ecological adaptation strategies ofsmall-scale fishers in the coastal area for climate change(Mohammad Mozumder)
09:14 - 09:16 Transport and heat loss of the Pacific Summer Water inthe Arctic Chukchi Sea northern slope: mooring data
analysis (Miaki Muramatsu)
6

【Day 4: 2 June (Wed) (cont.)】 (Time in Japan Standard Time, JST)
09:16 - 09:18 Influence of physical oceanographic condition totransportation of diatom and silicoflagellate particles inthe southwestern Canada Basin (Jonaotaro Onodea)
09:18 - 09:20 Stratification in the northern Bering Sea in early summerof 2017 and 2018 (Hiromichi Ueno)
09:20 – 09:22 International Convention and Prevention of Pollution:Heavy
Metal Concentration in the Bay of Bengal (Abu Hena
Muhammad Yousuf)
15:00 - 17:00 AnalogueART - PESAS Joint Workshop (Second Session)
・Using natural gradients to study the capacity of organisms to physiologically
adapt to future climate change (James Brown)
・Using pteropods as a model species to investigate the effect of large scalemosaics in ocean carbonate chemistry (Melissa Chierici, Kumiko Azetsu-Scott,
Agneta Fransson)
・Use of natural analogues to assess the effects of future change on
ecosystem services important for society (Jason Hall-Spencer)
・Relevance of historical ecology to contemporary and future socio-ecologicalconcerns (Ben Fitzhugh)・(To Be Determined ) (Spencer Wood)【Day 5: 3 June (Thu)】 (Time in Japan Standard Time, JST)
05:00-08:00 ESSAS Science Steering Committee Meeting※ Virtual Excursion (any time during the meeting)Upopoy (English site)(https://ainu-upopoy.jp/en/)(Chinese, Korean, Russian, Taiwanese, Thai versions are also available)
7

Abstract8

【Plenary Talk 1】「春の歌と⾵の物語: ⾵・海・氷・⼈々と太平洋ニシンとの関係―過去・現在・未来―」
A song of spring and a story of winds: The relationship among
Pacific herring (Clupea pallasii) , winds, sea, ice and people
from the past to the future
Naoki TOJO, Ph.D.
International Education Office (FDC/IEO), Faculty of Fisheries Sciences, Hokkaido
University
Pacific herring (Clupea pallasii) distributed over the North Pacific Ocean. As one ofsignificant fisheries resources, herring has sustained livelihoods of coastal communitiesof the northern Pacific Rim. In Bering Sea, sea ice and storms closes the mother sea formonths in the years, herring has been the first protein source after long winter for thenatives along Alaskan coast. Based on the socio-economic needs in 1990’s, Dr. Gordon
H. Kruse and I worked to investigate the variability of herring spawning timings andlocations with Alaska Department of Fish in the coast of Bristol Bay, Alaska. Since roeof herring was highly valuable as “KAZUNOKO”, it was important to predict when andfrom where herring comes to shore and to spawn at adequate gonad maturity for fishers.
We used geographic information system (GIS) to spatio-temporally collate and analyze
historical herring spawning observations and a variety of environmental variables,
including sea ice total concentration from National Snow and Ice Data Center, sea surface
temperature from Comprehensive Ocean-Atmosphere Data Set and time series of winds
and surface air temperature from the NCEP/NCAR Reanalysis and weather stations along
the coast. Significant statistical relationship was found between spawning timing andenvironmental variabilities, especially sea ice along dynamic herring migration pathways.
Spawning locations was also variable through the survey history. Wind-driven sea ice
dynamics most likely influences to herring pre-spawning behaviors. Besides, themodeled dynamic behaviors correspond to local indigenous knowledge. Recent years
with se ice decline, further monitoring and updates by integrative research has been
expected for sustainable relationship between herring, environment, and people of thenorthern Pacific Rim.

9

【Plenary Talk 2】
Assessing and managing fish stocks in a rapidly changing
environment
Franz Mueter
College of Fisheries and Ocean Sciences, University of Alaska Fairbanks

Warming oceans, the loss of sea ice, and changes in advection drive changes in highly
productive Subarctic marine ecosystems and the increasing borealization of Arctic
marine ecosystems. Borealization refers to the northward shift or expansion of marine
populations and communities, including commercially important fish species, into
Arctic waters. These shifts have been particularly pronounced on the major Arctic
inflow shelves, which are the gateways from the Atlantic and Pacific Oceans into theCentral Arctic Ocean (CAO), and have the potential to fundamentally transform Arctic
marine ecosystems. These changes can pose significant challenges for fisheries stock
assessment and management as some Subarctic fish stocks decline and others are
displaced or expand into new areas. Shifting stocks are a challenge for stock assessment
surveys as species move out of historically surveyed areas, for managers as changing
stock and fisheries interactions may lead to resource conflicts, and for international
institutions as stocks cross national boundaries or expand into the CAO. To meet thesechallenges, researchers will have to adopt new and cost-effective strategies formonitoring, managers have to be flexible to adapt to rapidly changing conditions, andenhanced international cooperation will be required to address transboundary issues andensure the conservation and sustainable management of living marine resources in the
CAO. Here I review these challenges and some of the emerging responses from theresearch community, management agencies and international institutions and provide
some recommendations for sustainable and healthy Arctic marine systems.

10【Plenary Talk 3】
Reframing the interface of science, policy and industry for the
better ecosystem governance in the Anthropocene
Aoi Sugimoto
Fisheries Resources Institute, Japan Fisheries Research and Education Agency

This presentation will explore the way to drive the transformative change ofenvironmental governance in the Anthropocene, using case studies in Okinawa andHokkaido, the most south and north part of Japan.
Global policy and science platform is increasingly recognizing the importance forengaging diverse perspectives from scientific disciplines, conservation practitioners aswell as those of local and indigenous communities to achieve desirable ecosystemgovernance (Díaz et al. 2018; Diaz et al. 2019; Pascual et al. 2017). Plural valuations ofhuman–nature relationships are the key for a better, more inclusive decision-making,which is demonstrated by my case study in Yaeyama archipelago applying a network
analysis on qualitative text contents. Based on, and in addition to the sound scientificfinding, this case study paid a strong effort for communication of those findings, such as
collaborative works with artists, designers and musicians. Through this innovative
process of collaboration, I became aware of the possibility of multiscale governancewhich goes beyond the conventional science-policy interface, reaching much wider
audiences outside of academics and governments. This presentation will describe thisprocess, clarifying the challenges and potentials of such approach to share and trigger
future opportunities among diverse stakeholders related to ecosystem governance under
the umbrella of IMBER. I hope that my methods and findings will be applied to otherareas, especially to the local and indigenous communities of Asia-Pacific where biocultural diversity is extremely rich but also facing crisis, and that the transformativechange of ecosystem governance in the Anthropocene can be driven.

11

Zooplankton biomass and biodiversity on the Sofala Bank,
Mozambique
Ceiça A. Chioze1, Bernadino S. Malauene1 and Jenny A. Huggett2,3
1

Instituto Nacional de Investigação Pesqueira, Av. Mao-Tsé-Tung 309, Maputo, Mozambique
Oceans and Coastal Research, Department of Environmental Affairs, Private Bag X4390,
Cape Town 8000, South Africa
3
Department of Biological Sciences and Marine Research Institute, University of CapeTown, Private Bag X3, Rondebosch 7701, South Africa
2

Background: There have been relatively few zooplankton studies in the Western Indian Oceanin general, and over the Mozambique shelf in particular, although there has been interest in
recent years in ecosystem functioning related to mesoscale eddies in the Mozambique Channel.
Data from phytoplankton studies indicate the most productive areas over the Mozambican shelf
are Delagoa Bight in the south, the central Sofala Bank, influenced by seasonal nutrient input
from the Zambezi delta, and Angoche in the north. The overarching objective of this project is
to investigate patterns of abundance, biomass and species diversity of zooplankton
communities on the Sofala Bank during October 2017, and to explore relationships with theassociated physical, chemical and biological environment.
Methods: Zooplankton sampling was conducted off the coast of Mozambique – Sofala Bank
during the first IIOE-2 survey on the SA Agulhas II in October 2017. Samples were collectedfrom 44 stations using a Bongo net (200 µm) towed obliquely from a maximum depth of 200
m. Samples were preserved in 4% buffered formaldehyde for later identification by microscope.
In the laboratory, samples were decanted into measuring cylinders and allowed to settle for 24hours, after which settled volume measurements were taken. Biovolume (ml/m3) was
calculated by dividing the settled volume (ml) by the volume of water filtered by the net (m3)at each station.
Results: Mean zooplankton biovolume over the Sofala Bank (between Beira and Angoche) was
0.19 ml/m3, ranging from 0.04 to 0.95 ml/m3. Greatest concentrations of zooplankton werelocated to the south (0.95 ml/m3) and north (0.82 ml/m3) of the Zambezi delta, in water depthsof <50m. The southern maximum was associated with a region of relatively warm (26.4°C)
and fresh (34.9 PSU) water presumably related to river outflow.
Conclusions: Zooplankton biomass was greatest close to the shore in the southern sector of the
Sofala Bank off the Zambezi River mouth, presumably related to the river plume, with low
biomass observed offshore.

12Assessing and managing fish stocks in a rapidly changing
environment
Franz Mueter
College of Fisheries and Ocean Sciences, University of Alaska Fairbanks

Warming oceans, the loss of sea ice, and changes in advection drive changes in highly
productive Subarctic marine ecosystems and the increasing borealization of Arctic
marine ecosystems. Borealization refers to the northward shift or expansion of marine
populations and communities, including commercially important fish species, into
Arctic waters. These shifts have been particularly pronounced on the major Arctic
inflow shelves, which are the gateways from the Atlantic and Pacific Oceans into theCentral Arctic Ocean (CAO), and have the potential to fundamentally transform Arctic
marine ecosystems. These changes can pose significant challenges for fisheries stock
assessment and management as some Subarctic fish stocks decline and others are
displaced or expand into new areas. Shifting stocks are a challenge for stock assessment
surveys as species move out of historically surveyed areas, for managers as changing
stock and fisheries interactions may lead to resource conflicts, and for international
institutions as stocks cross national boundaries or expand into the CAO. To meet thesechallenges, researchers will have to adopt new and cost-effective strategies formonitoring, managers have to be flexible to adapt to rapidly changing conditions, andenhanced international cooperation will be required to address transboundary issues andensure the conservation and sustainable management of living marine resources in the
CAO. Here I review these challenges and some of the emerging responses from theresearch community, management agencies and international institutions and provide
some recommendations for sustainable and healthy Arctic marine systems.

13Inter-annual variability of phytoplankton community structure in
the Pacific Arctic Region
1

Amane Fujiwara, 1Shigeto Nishino, 2Toru Hirawake, 3Koji Suzuki, 1Takashi Kikuchi

1

Institute of Arctic Climate and Environment Research, Japan Agency for Marine-Earth
Science and Technology (JAMSTEC)
2
Bioscience Group, National Institute of Polar Research Japan
3
Faculty of Environmental Earth Science, Hokkaido University
The Arctic marine ecosystem has been facing on extremely variable environmental changes(e.g., sea ice decline, warming, and freshening). The lower trophic organisms are known to
response quickly to such changes because of their short life cycle. Since the Arctic marine food
web forms short and efficient energy transport system, even the small changes in the lower
trophic organisms can have a large cascading impact on whole marine ecosystem. In this study,
we evaluated the relationship between phytoplankton community structure and environmental
variables using in situ data acquired during Japanese Arctic research cruises conducted duringlate summers from 2008 to 2017. The phytoplankton community group were able to divided
into several major clusters using pigment signatures, and each cluster showed significantly
different adaptation to water mass characteristic. The most productive and diatom dominatedcommunity was found in the Bering Shelf Water (BSW) occupied shallow shelf region mostly
in cold years. In contrast, less productive community with larger diversity appeared in the shelfregion when the warmer Alaskan Coastal Water (ACW) spread years. The ACW adapted
community can even be transported to the northern basin region in less ice years and canovertake cold adapted basin community in dominance. Our results imply that spatial prominentof water masses strongly affect phytoplankton community structure in PAR, which in turn canhave a large impact on the areal biological productivity.

14

Impact of sea-ice dynamics on the spatial distribution of
diatom resting stages in sediments of the Pacific-Arctic Ocean
Yuri Fukai1,2, Kohei Matsuno2,3, Amane Fujiwara4, Koji Suzuki1,5, Mindy Richlen6,
Evangeline Fachon6, Donald M. Anderson6
1

Graduate School of Environmental Science, Hokkaido University, Japan,
fukai@ees.hokudai.ac.jp
2
Faculty/Graduate School of Fisheries Sciences, Hokkaido University, Japan
3
Arctic Research Center, Hokkaido University, Japan
4
Japan Agency for Marine-Earth Science and Technology, Japan
5
Faculty of Environmental Earth Science, Hokkaido University, Japan
6
Biology Department, Woods Hole Oceanographic Institution, USA
The Pacific-Arctic Ocean is characterized by seasonal sea-ice, the spatial extent andduration of which varies considerably. In this region, diatoms are the dominantphytoplankton group during spring and summer. To facilitate survival during periods thatare less favorable for growth, many diatom species produce resting stages that settle tothe seafloor and can serve as a potential inoculum for subsequent blooms. Since diatom
assemblage composition is closely related to sea-ice dynamics, detailed studies ofbiophysical interactions are fundamental to understanding the lower trophic levels of
ecosystems in the Pacific-Arctic Ocean. One way to explore this relationship is bycomparing the distribution and abundance of diatom resting stages with patterns of seaice coverage. In this study, we quantified viable diatom resting stages in sediments in2018 and explored their relationship to sea-ice extent during the previous winter. Diatom
assemblages were clearly dependent on the variable timing of the sea-ice retreat andaccompanying light conditions. In areas where sea-ice retreated earlier, open-water
species such as Chaetoceros spp. and Thalassiosira spp. were abundant. In contrast,
proportional abundances of Attheya spp. and pennate diatom species that are commonly
observed in sea-ice were higher in areas where diatoms experienced higher light levels
and longer day length in/under the sea-ice due to the late seasonal ice retreat. This study
demonstrates that sea-ice dynamics are an important determinant of diatom species
composition in the Pacific-Arctic.

15

Climate change adaptation in aquaculture: a systematic review
Eranga K. Galappaththi1, Stephanie T. Ichien2, Amanda A. Hyman3, Charlotte J. Aubrac1 andJames D. Ford4
1

Department of Geography, McGill University, Montreal, QC, Canada
College of Agricultural Science, Oregon Sea Grant, Oregon State University, Corvallis, OR, USA
3
Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN, USA
4
Priestley International Centre for Climate, University of Leeds, Leeds, UK
2This study conducts the first systematic literature review of climate change adaptation inaquaculture. We address three specific questions: (i) What is aquaculture adapting to? (ii) How isaquaculture adapting? and (iii) What research gaps need to be addressed? We identify,
characterise and examine case studies published between 1990 and 2018 that lie at theintersection of the domains of climate change, adaptation and aquaculture. The main areas of
documented climate change impacts relate to extreme events and the general impacts of climatechange on the aquaculture sector. Three categories of adaptation to climate change are identified:coping mechanisms at the local level (e.g. water quality management techniques), multilevel
adaptive strategies (e.g. changing culture practices) and management approaches (e.g. adaptation
planning, community-based adaptation). We identify four potential areas for future research:
research on inland aquaculture adaptation; studies at the household level; whether different
groups of aquaculture farmers (e.g. indigenous people) face and adapt differently to climatechange; and the use of GIS and remote sensing as cost-effective tools for developing adaptation
strategies and responses. The study brings essential practical and theoretical insights to theaquaculture industry as well as to climate change adaptation research across the globe.

16

1st circular of Program 2021 ESSAS Annual Science Meeting

Underwater soundscape and its temporal variability in the East
Siberian Sea
Dong-Gyun Han1, Jongmin Joo2, Wuju Son1,3, Kyoung Ho Cho1, Jee Woong Choi4, Eun Jin
Yang1, Jeong-Hoon Kim5, Sung-Ho Kang1, and Hyoung Sul La1
1

Division of Ocean Sciences, Korea Polar Research Institute, Incheon, 21990, Republic ofKorea.
2
Policy Support Team, National Air Emission Inventory and Research Center, Cheongju,
28166, Republic of Korea.
3
Department of Polar Science, University of Science and Technology, Daejeon, 34113,
Republic of Korea.
4
Department of Marine Science & Convergence Engineering, Hanyang University ERICA,
Ansan, 15588, Republic of Korea.
5
Division of Life Sciences, Korea Polar Research Institute, Incheon, 21990, Republic ofKorea.
The East Siberian Sea is one of the least studied regions in the Arctic Ocean and there aremany knowledge gaps in the underwater sound of the East Siberian Shelf. We measured theunderwater sound in the East Siberian Sea using an autonomous passive acoustic recorderfrom August 2017 to August 2018. Sea ice concentration, sea ice drift speed, draft depth,
ocean current speed and wind speed data were collected to derive the relationship with theunderwater soundscape. We found that underwater sound level is negatively correlated withthe sea ice concentration and identified its seasonal variability. The sound level was relatively
high in summer when the sea ice concentration varied largely or open water conditions. The
conspicuous sound sources were identified and contributions of the anthropogenic and natural
physical sound source to the increased ambient noise level were estimated in a given period.
In addition, the results of previous studies on the ambient noise in the Arctic Ocean werecollected and the median spectra of each region were compared. From the comparison results,
the East Siberian Sea was relatively quiet region in the Arctic Ocean. More details will be
discussed in the meeting.

17

Physical manifestations and ecological implications of Arctic
Atlantification
Ingvaldsen, R.B., Assmann, K. M., Dolgov, A.V., Fossheim, M., Polyakov, I. V. Primicerio, R.
The Atlantic gateway to the Arctic Ocean is strongly influenced by vigorous inflows of warm
Atlantic Water, whose high-latitude impacts are rapidly strengthening. This presentation
discusses various manifestations of this “Atlantification” in a hotspot region of climate change
spanning from the southern Barents Sea to the Eurasian Basin. There is a host of changes
associated with Atlantification, with warmer ocean, weaker stratification, enhanced upper
ocean mixing, and enhanced air-ice-ocean coupling – all leading to sea ice loss. Key
mechanisms driving the physical changes include reduced heat loss amplifying temperature
anomalies, changes in vertical structure due to loss of sea ice, and positive ice/ocean heat
feedback. Progressing Atlantification seems to be characterized by increased dominance ofregional processes becoming part of the Atlantification. Arctic ecology is characterized byenvironmental conditions that in the past precluded colonization by boreal species and theestablishment of a more diverse pelagic compartment. Atlantification promotes invasion by
boreal species, which modify Arctic biodiversity, community structure, food web organization,and ecosystem functioning. This study increases the understanding and the ability to predictchanges in the Arctic driven by ongoing and future climate change, which is of relevance toscientists, managers, and society at large.

18

Increasing zooplankton biomass associated with sea ice loss inthe western Arctic Ocean and its ecological impacts
Motoyo Itoh1, Minoru Kitamura1, Amane Fujiwara1, Eddy C. Carmack2, Kazuo
Amakasu3, Koichi Ara4, Mario Uchimiya5, Toru Hirawake6, Jonaotaro Onodera1,
Shigeto Nishino1 and Takashi Kikuchi1
1

Institute of Arctic Climate and Environment Research, Japan Agency for Marine-Earth
Science and Technology, Yokosuka, Kanagawa, Japan
2
Fisheries and Oceans Canada, Institute of Ocean Sciences, Sidney, British Columbia,
Canada3
Tokyo University of Marine Science and Technology, Minato-ku, Tokyo, Japan
4
Department of Marine Science and Resources, College of Bioresource Sciences, Nihon
University, Fujisawa, Kanagawa, Japan
5
RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, Japan
6
Faculty of Fisheries Science, Hokkaido University, Hakodate, Hokkaido, Japan

Sea ice cover is rapidly declining due to global warming. This change is accompanied
by increases in sea surface temperature and phytoplankton primary production in thewestern Arctic Ocean. However, their influence on marine ecosystems remains unclear,as few studies have conducted ecological monitoring at decadal time scales. Comparing
mooring-based acoustic backscattering data collected during periods of both high (2000－2003) and low sea ice coverage (2010—2013) in the Chukchi Sea, western Arctic
Ocean, we show that annual mean zooplankton biomass has increased 1.6-fold between
the two periods. This biomass change increased the grazing pressure on phytoplankton
from zooplankton based on a theoretical food requirement model. Consequently, supplyof sinking carbon to benthic organisms is expected to decrease during summer, despite
phytoplankton production increasing. Thus, the Chukchi Sea ecosystem is likely to be
shifting away from a pelagic-benthic coupled ecosystem toward a pelagic-dominatedsystem in which primary production is not directly connected to the benthic carbon
cycle due to increased grazing by pelagic zooplankton.

19Inter-annual changes of the mesozooplankton community
structure in the Western Arctic Ocean during summers of 20152018

Jee-Hoon Kim1, Hyoung Sul La1, Kyoung-Ho Cho1, Jinyoung Jung1, Sung-Ho Kang1, Eun Jin
Yang1*

1

Division of Polar Ocean Science, Korea Polar Research Institute, Incheon 21990, Republicof Korea
The Arctic Ocean is the forefront area of climate change research, being the first to respond toclimate change on a global scale and highly sensitive to tiny oceanographic changes. The frozen
Arctic Ocean, covered with thick sea ice, was an inaccessible area, but research on the Arctic
Ocean has been actively conducted since the construction of the icebreaker research vessel(IBRV). This research is the first comprehensive Arctic mesozooplankton study conductedusing the Korean IBRV Araon. Mesozooplankton samples were collected in the western Arctic
Ocean from 2015 to 2018. A total of 43 species belonging to 14 taxa were identified andanalyzed for ocean biological and community ecological studies. The most predominant taxon
was copepods, of which Calanus glacialis was the most dominant species amongholozooplankton. We describe the Inter-annual composition and structure of themesozooplankton community in the Western Arctic Ocean. The distribution and structure of
the meso-zooplankton communities showed variations over large spatial scales in the western
Arctic waters due to variations in environmental factors, although it appears to be determinedprimarily by “water mass”.

20Melina Kourantidou* & Brooks A. Kaiser
Management & Economics of Resources & Environment Research Group,
Dept of Sociology, Environmental and Business Economics, University of Southern Denmark

Capital investments for the Norwegian Red King Crab: A Tale of Ecologicaland Community Resilience
Abstract
The importance of onshore infrastructure for supporting coastal fisheries has long been acknowledged; its role in remote and geographically challenged fishing communities in theNordic Arctic has visibly impacted community structure and development. This paper explores the Red King Crab (RKC) fishery in Norway and the ways in which its management
has been changing the socioeconomic landscape in Northern Finnmark since the beginningof commercial exploitation in the early 2000’s. The RKC in the Barents Sea is an intentionally introduced species that is viewed both as a nuisance and as a valuable economic
resource. This induces ambivalent preferences among local stakeholders and decision-makers
in Norway. Low harvesting costs, uncertain ecosystem losses and ongoing infrastructure investment in onshore landing facilities all shape stakeholders’ myopic interests in Norway infavor of a long-term management of the fishery. Simultaneously the political willingness to
support local coastal communities and livelihoods in northern Norway provides significant
impetus for maintaining a long-term stock, particularly in Eastern Finnmark. The ongoing infrastructure investments favor regional stakeholders over more diffuse and less clearly
identified interests in the ecosystem changes induced by the invasive crab. With this paper, we highlight the path dependencies created by infrastructure development and seek to
identify trade-offs inherent in the management of the invasion for ecological and community
resilience.
Keywords: Commercially Valuable Invasions, Fisheries Management, Red King Crab,Livelihood Trajectories in Northern Fisheries, Barents Sea Fisheries*Corresponding Author, mkour@sdu.dk, Degnevej 14, 6705 Esbjerg Ø, Denmark

1

21

Studies on Limacina helicina at Mombetsu in the southern Okhotsk Sea
Kohei Matsuno1,2, Nao Sato1, Hiromi Kasai3, Seiji Katakura1,4, Keisuke Shimizu5, Katsunori Kimoto6,
Katsushi Iwamoto1,4
Faculty/Graduate
SchoolofFisheries
Sciences,
Hokkaido
University,
Japan,
k.matsuno@fish.hokudai.ac.jp
2Arctic Research Centre, Hokkaido University, Japan
3
Fisheries Resources Institute, Japan Fisheries Research and Education Agency, Japan
4
City of Mombetsu, Japan
5
Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The
University of Tokyo, Japan
6
Research Institute for Global Change, Japan Agency for Marine-Earth Science and Technology, Japan
1

Long-term and high-frequent monitoring of hydrography and plankton have been
performed from 1997 to present at the Okhotsk Tower located at Mombetsu, in thesouthern Okhotsk Sea off Hokkaido. The region has two unique features; south end of
the seasonal sea-ice area in the northern hemisphere, many species are same to Arctic
phytoplankton and zooplankton species. Because of these features, observation in
winter (sea-ice coverage season) gives us good opportunities to study relation between
sea-ice and lower trophic levels. Some linkages between them were already suggested
at the region, but still relatively poorly understood. In this study, we will introduce
outcomes regarding to lower trophic levels (especially, Limacina helicina) frommonitoring at the tower and ship-board observation using Icebreaker Garinko II at
Mombetsu in winter season.

Presentation type: poster

22

Impacts of meltwater discharge from marine-terminating glaciers on the protist
community in Inglefield Bredning, northwestern Greenland
Kohei Matsuno1,2, Naoya Kanna2,3, Shin Sugiyama4,2, Atsushi Yamaguchi1,2, Eun Jin Yang4
1

Faculty/Graduate
SchoolofFisheries
Sciences,
Hokkaido
University,
k.matsuno@fish.hokudai.ac.jp
2Arctic Research Centre, Hokkaido University, Japan
3
Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Japan
4
Institute of Low Temperature Science, Hokkaido University, Japan
5
Division of Polar Ocean Science, Korea Polar Research Institute, Republic of Korea

Japan,

To evaluate the effects of meltwater discharge from marine-terminating glaciers on afjord protist community in northwestern Greenland during summer, we investigated the
distribution, abundance and biomass of the protist community and their relationships
with hydrographic parameters. In the standing stock of protists, dinoflagellates (46.4%)
and oligotrich ciliates (39.5%) were dominant throughout the study region. According
to the vertical distribution, oligotrich ciliates were abundant in the surface layer, mainly
due to suitable food conditions (including the diatom and nanoflagellate abundances).
Near glaciers, relatively high chl a concentrations were found in the subsurface layers
associated with the low-temperature, high-turbidity and slightly high nutrient levels,
indicating that the nutrient inputs from the upwelling glacial meltwater plume were
driving primary production. Large-sized Protoperidium spp. occurred only at stations
near glaciers where nutrients were abundant, and heterotrophic dinoflagellates showedstrong relationships with nanoflagellates. These findings suggest that the upwellingassociated with subglacial meltwater discharge can stimulate autotrophic nanoflagellate
production, resulting in increases in ciliate and heterotrophic dinoflagellate production.

Presentation type: poster23

Response of zooplankton community with early sea-ice reduction in the northern
Bering Sea during summers 2017, 2018
Fumihiko Kimura1, Kohei Matsuno1,2, Yoshiyuki Abe3, Atsushi Yamaguchi1,2Faculty/Graduate
SchoolofFisheries
Sciences,
Hokkaido
University,
Japan,
k.matsuno@fish.hokudai.ac.jp
2Arctic Research Centre, Hokkaido University, Japan
3
Research Development Section, Office for Enhancing Institutional Capacity, Hokkaido University,
Japan
1

Remarkable early sea-ice reduction was observed in the northern Bering Sea during
2018. Due to the unusual hydrographic situation, several trophic levels responded;
delayed phytoplankton bloom, phytoplankton community change, northward shift offishes, but response of zooplankton community is still unclear. Thorough this study, weinvestigated the zooplankton community in the northern Bering Sea during summers in2017 and 2018, and evaluate the effects of early sea-ice melt on zooplankton
community and population stage structure of large copepods. Based on cluster analysis,
five zooplankton communities were identified. In the Chirikov Basin, year changes on
the zooplankton community were found. In 2017, the zooplankton community included
abundant pacific copepods transported by Anadyr water. While in 2018, small
copepods were dominated, this may be related with early sea-ice reduction.
Comparison the population structure for large copepods (Calanus glacialis/marshallae
and Metridia pacifica) between 2017 and 2018, clear difference was detected. In 2018,higher abundances with dominance of younger stages of them were observed. This wascaused mainly the different onset timing of phytoplankton bloom associated with
sea-ice melt and water stratification. Eventually, early sea-ice melt suggested delayed
reproduction timing of the large copepods with late phytoplankton bloom.
Presentation type: oral

24

Changes and future predictions of Oyashio Intermediate Water, a key
water mass for biological production*Vigan Mensah 1, Kay I. Ohshima 1
1

Institute of Low Temperature Science, Hokkaido University, JapanThe western subarctic Pacific exhibits major biological productivity and possesses one of the largest
biological CO2 drawdown in the world. This biological productivity is fed by the Oyashio Current
and its two source waters: Western Subarctic Water, which supplies nutrients from the subarctic
Pacific, and cold Okhotsk Sea Intermediate Water (OSIW), which supplies iron from the Sea of
Okhotsk. As iron content is a limiting factor for biological productivity, it is essential to understandand predict the variability in OYW properties in a changing climate, and specifically the content of
OSIW in OYW (mixing ratio). Here, we created seasonal climatologies of water properties tounderstand how climate change (~50 years trend) and the 18.6-year tidal cycle affect the Oyashio
Intermediate Water (OYW). We found that due to climate change, the “recipe” of OYW is modified
mainly in winter via decreased OSIW outflow. This yields a warmer, and possibly less iron-rich
Oyashio. Conversely, the outflow of OSIW is increased (decreased) in high-tide (low-tide) years.
We then provide a 20-year prediction of OYW temperature and mixing ratio. We predict that the
opposite effects of the climate change and high tide will lead to stagnation of the OYW properties
in the 2020s. However, OYW warming will be accelerated in the 2030s due to the combined effects
of climate change and low-tide. Besides, we found that OYW temperature will increase by 1 °C,
and the mixing ratio of OSIW in OYW will decrease by 50% between 1960 and 2040, which might
greatly impact biological productivity, fisheries, and carbon drawdown in the North Pacific.

25

Institutional innovation for the cooperative utilization ofcross-domain marine space resources in the GuangdongHong Kong-Macao Greater Bay Area
Chen Mingbao

At present, reclamation is no longer an effective way to expand the urban space of the
Guangdong-Hong Kong-Macao Greater Bay Area（GBA）. How to efficiently use theexisting marine space resources to promote the sustainable development of the marine
economy and promote cooperation in the GBA? It is an urgent problem to be solved.
Under the guidance of MEBM theory, this article establishes an analysis framework of
institutional supply and demand for the cooperative utilization of cross-domain marine
resources, combined with the institutional characteristics of the GBA, and analyzes theinstitutional defects and the possible space for institutional innovation in the process ofcooperative utilization of marine space resources in the GBA. The research shows thatmarine space resources are the common development space of the GBA and also an
important carrier for Hong Kong and Macao to integrate into the overall developmentof China. The cooperative utilization of marine space resources can promote thedevelopment of the GBA. The direction of institutional innovation for marine spaceresource cooperation in the GBA should be based on the requirements of common
development and MEBM, break through administrative boundaries, highlight theirrespective advantages, and innovate new mechanisms conducive to the cooperative
utilization of marine space resources in the GBA, so as to promote the utilization andprotection of marine resources and realize the harmonious development of human andocean.

26

Reframing the interface of science, policy and industry for the
better ecosystem governance in the Anthropocene

Aoi Sugimoto
Fisheries Resources Institute, Japan Fisheries Research and Education Agency

This presentation will explore the way to drive the transformative change ofenvironmental governance in the Anthropocene, using case studies in Okinawa andHokkaido, the most south and north part of Japan.
Global policy and science platform is increasingly recognizing the importance forengaging diverse perspectives from scientific disciplines, conservation practitioners aswell as those of local and indigenous communities to achieve desirable ecosystemgovernance (Díaz et al. 2018; Diaz et al. 2019; Pascual et al. 2017). Plural valuations ofhuman–nature relationships are the key for a better, more inclusive decision-making,which is demonstrated by my case study in Yaeyama archipelago applying a network
analysis on qualitative text contents. Based on, and in addition to the sound scientificfinding, this case study paid a strong effort for communication of those findings, such as
collaborative works with artists, designers and musicians. Through this innovative
process of collaboration, I became aware of the possibility of multiscale governancewhich goes beyond the conventional science-policy interface, reaching much wider
audiences outside of academics and governments. This presentation will describe thisprocess, clarifying the challenges and potentials of such approach to share and trigger
future opportunities among diverse stakeholders related to ecosystem governance under
the umbrella of IMBER. I hope that my methods and findings will be applied to otherareas, especially to the local and indigenous communities of Asia-Pacific where biocultural diversity is extremely rich but also facing crisis, and that the transformativechange of ecosystem governance in the Anthropocene can be driven.

27

Marine Ecosystem Variations over the North Pacific and their
Linkage to Large-Scale Climate Variability and Change
Emi Yati 1,6, Shoshiro Minobe1, 2, Nathan Mantua3, Shin-ichi Ito4, Emanuele Di
Lorenzo5
1

Department of Natural History Sciences, Graduate School of Science, Hokkaido
University, Sapporo, Japan2
Department of Earth and Planetary Sciences, Faculty of Science, Hokkaido University,
Sapporo, Japan
3
Fish Ecology Division, Southwest Fisheries Science Center, National Marine FisheriesService, National Oceanographic and Atmospheric Administration, Santa Cruz,
California, USA.
4
Atmosphere and Ocean Research Institute, University of Tokyo, Kashiwa, Japan
5
School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta,
Georgia, USA.
6
Remote Sensing Application Center, Indonesian National Institute of Aeronautics andSpace, Jakarta, Indonesia

In order to understand how North Pacific (NP) marine ecosystem have varied, 120
marine biological time series for both the western (29 time series) and eastern (91 timeseries) NP were analyzed with a Principal Component Analysis (PCA) for the period
1965 to 2006. This is the first attempt to conduct a multivariate analysis for a large
number of marine biological data in the western and eastern NP combined. We used
Monte-Carlo simulation to evaluate confidence levels of correlations and explained
variance ratio of PCA modes with accounting for auto-correlation within the analyzed
time series. All first mode principal components (PC1s), which are the time coefficientsof the first PCA modes, calculated for the data in the whole, western, and eastern NP
exhibit a long-term trend. The PC1s were associated with an overall increase of Alaskan
and Japan/Russian salmon, and decreases of groundfish across the basin. This mode wasclosely related to the warming of sea-surface temperature over the NP and over the
global oceans, thereby suggesting that the strongest mode of the NP marine ecosystem
was already influenced by global warming. The eastern NP PC2, characterized by multi
decadal variability, was correlated positively with salmon and negatively withgroundfish. On the other hand, the western NP PC2 exhibited slightly shorter timescaleinterdecadal variability than the eastern NP PC2 and was negatively correlated withzooplankton and two small pelagic fish time series around Japan. The eastern NP PC228

was the most strongly related to the Pacific (inter-)Decadal Oscillation index, while thewestern NP PC2 was most closely related to the North Pacific Gyre Oscillation index.
Consequently, the present analysis provides a new and unified view of climate change
and marine ecosystem variations across the western and eastern NP. In particular, it issuggested that global warming has already substantially influenced the North Pacificmarine ecosystem. It is suggested that the groundfish may suffer more than pelagic fish
due to the future global warming.

29

Understanding the Current Status of Seawater pH Changes Near
Scallop Aquaculture Facilities in Northern Japan

Ayumi Mori 1, Takeshi Yoshimura 2, Isao Kudo 2, Koichi Sakaguchi 3
1. Graduate school of Environmental Science, Hokkaido University
2. Faculty of Fisheries, Hokkaido University
3. Aquaculture Fishery Cooperative of Saroma LakeIn recent years, ocean acidification has gained attention, and there has been growing concern
regarding the decrease of ocean pH. Although seasonal and diurnal changes in pH may be greater incoastal areas than in the open ocean, the changes are not well understood. As pH decreases, thesaturation state of calcite (ΩCa), a type of calcium carbonate, decreases, affecting the survival andgrowth of calcifying organisms. Calcite-forming scallops (Patinopecten yessoensis) are one of themost important fishery resources in northern Japan. Their growth may be inhibited by decreased pH.
However, the current situation remains unclear. Therefore, in this study we conducted surveys tounderstand the current state of pH decrease near scallop aquaculture facilities in Lake Saroma andFunka Bay in Hokkaido, as well as Mutsu Bay in Aomori, Japan. Furthermore, the observed values
were used to predict pH and ΩCa values at the end of this century (2081-2100) under different RCP
scenarios. The results show that seasonal pH changes were similar in the three areas, although themagnitude of change differed among sites. The largest range of pH changes (7.5-8.3) was observedin Lake Saroma, and the lowest values were observed in the bottom layer in summer when organic
matter decomposition occurs. In addition, ΩCa in Lake Saroma decreased with decreasing pH, as well
as a decrease in water temperature and salinity in all layers in winter. Thus, we demonstrate that thebottom layer in summer and all layers in winter should be considered for scallop growth inhibitionsin Lake Saroma. Predictions based on these results showed that scallop cultivation would be still
possible under RCP 2.6, but may be impossible due to significantly reduced growth in all areas andseasons under RCP 8.5.

30

Social, economic, and ecological adaptation strategies of small-scale
fishers in the coastal area for climate change
Mohammad Mozumder
University of Helsinki, Finland

Small-scale fisheries are undeniably important for livelihoods, food security and income aroundthe globe. However, they face major challenges, including global market and demographic shifts,
policy changes and climate variations that may threaten the wellbeing, health, and safety of fishingcommunities. Climate change and extreme weather pose significant and long-term risks to fisheries
in many tropical developing countries including Bangladesh, like disruption of fishing operations
and fish production. Coastal fishing communities lack the economic, social, and political power toimprove their resilience to these stressors. Hilsa (Tenualosa ilisha) is Bangladesh's most valuable
fish species - nutritionally, economically, and culturally. Adoption of coping strategies to theimpacts of climate change is crucial for the hilsa fishery, and the fishing communities depend on
it. This research focuses on the liable determinants and dimension of hilsa fishing community
beliefs of, and adaptation to, climate change and recommends policies for adaptation. The present
study applies adaptation theories to shape the research and related interpretation. A mixed method
research approach was used to investigate fundamental dimensions of community perception ofclimate change and adaptation, drawing on multiple sources of evidence: participant observation,
household survey, in depth-individual interviews, focus group discussions, key informant
interviews and secondary sources. Respondents had clear perceptions about climate change as aform of changes in rainfall, seasonal patterns, increased temperatures, and salinity. Such changes
threaten biodiversity and could lead to changes in migration patterns of fish, declining fish stocks.
Hilsa fishers believed that adaptation to climate change needs measures that simultaneously reducepoverty, protect, or restore biodiversity and ecosystem services, by getting more fishing inputs andmodern equipment, awareness and information, weather observation and alternative business. It is
hoped that this research will serve as a food of thought how fisher’s preferences and adaptation
practices including fisher's social, economic, and traditional knowledge can be incorporated into
formal adaptation policies.

31

Transport and heat loss of the Pacific Summer Water in the
Arctic Chukchi Sea northern slope: mooring data analysis
Miaki Muramatsu1,2, Hiromichi Ueno1, Eiji Watanabe2, Motoyo Itoh2 and Jonaotaro
Onodera2
1

Graduate School of Fisheries Sciences, Hokkaido University, 3-1-1 Minato-cho,
Hakodate, 041-8611, Japan
2
Institute of Arctic Climate and Environment Research, Japan Agency for Marine-Earth
Science and Technology, 2-15 Natsushima-cho, Yokosuka, 237-0061, Japan
We investigated the transport and heat loss of the Pacific Summer Water (PSW) along the
Chukchi Sea northern slope using the temperature, salinity and velocity data of themooring time series obtained in 2003–2005 (Period 1) and 2015–2019 (Period 2). The
PSW at Stations HSN and NHC on the Chukchi Sea northern slope was warmer andfresher in Period 2 than in Period 1. Results from a lag correlation analysis of thetemperature time series provide quantitative evidence to suggest that the PSW wastransported from Barrow Canyon to Stations HSN and NHC by the northwestward
Chukchi Slope Current. The advection time was 7–87 days. The temperature and salinity
mostly decreased during PSW transport. Vertical mixing with the surface cold water could
be a potential factor for temperature decrease. This decrease in Period 2 were higher thanthat in Period 1. This large decrease was probably influenced by stratification rather thanwind conditions.

32

Highlights of the R/V Mirai Arctic Ocean survey in 2020
Shigeto Nishino1, Amane Fujiwara1, Motoyo Itoh1, Jonaotaro Onodera1, Akihiko
Murata1,2,and Takashi Kikuchi1
1

Institute of Arctic Climate and Environment Research, Japan Agency for Marine-Earth

Science and Technology (JAMSTEC)
2

Global Ocean Observation Research Center, Japan Agency for Marine-Earth Scienceand Technology (JAMSTEC)
Since spatial and temporal variability is inherently large in the Arctic Ocean, weurgently need baseline data for the Arctic Ocean as a whole to prepare for the further
changes to come. Critically needed understandings would be advanced from acoordinated multi-ship, multi-nation pan-Arctic ship-based sampling campaign, basedon shared state-of-the-art protocols for data collections and sharing and carefullyplanned ship tracks during the same period. This could allow for a synoptic view of thetotality of hydrographic and ecosystem changes taking place in the Arctic Ocean andfacilitate advancing model development using integrated data sets to predict the futurestate of the Arctic. To obtain such baseline data, we have planned a pan-Arctic research
program, the Synoptic Arctic Survey (SAS), with a goal of conducting it in 2020 and
2021. In 2020, under the ArCS II project in collaboration with SAS, the Research
Vessel (R/V) MIRAI conducted hydrographic and biogeochemical surveys in the
Chukchi Sea and the southern Canada Basin. Here we present the following 3 topics.
1) Biological hotspot in the southern Chukchi Sea was not maintained in October 2020.
Surface nitrogenous nutrients were not depleted and chlorophyll concentration was
lower than usual in autumn.
2) In the marginal ice zone, chlorophyll concentration was relatively high at a seasonal
pycnocline (~ 20 m) and below a meltwater front.
3) Aragonite super-corrosive water was found on the Chukchi Plateau, a fishable area (<2000 m). The corrosive water distribution may be controlled by the extent of
Beaufort Gyre. Monitoring of the corrosive water in the Pacific Arctic including thefishable area is necessary under international collaborations of SAS and beyond.

33

Two species of seabirds used contrasting marine habitat
across the cold water belt along the coast of northern
Hokkaido in the southwestern Okhotsk Sea
B. Nishizawa, J. Okado, Y. Mitani, T. Nakamura, A. Yamaguchi, T. Mukai & Y. Watanuki
To understand the biophysical factors affecting density of foraging seabirds across thecold-water belt in the southwestern Okhotsk Sea, we conducted a one-day (180 km
transect length) shipboard seabird survey off the northeastern coast of Hokkaido during
summer in 2019, concurrently with acoustic observations of potential prey (zooplankton
and fish) biomass, thermosalinograph measurements, and CTD observations.
Planktivorous Short-tailed Shearwaters (Ardenna tenuirostris, 66% of total birds) andpiscivorous Rhinoceros Auklets (Cerorhinca monocerata, 28%) were dominant and used
contrasting foraging habitat. The large foraging flock of shearwaters was observed in the
cold-water belt zone, including its fronts with coastal Soya Warm Current Water and theoffshore Fresh Surface Okhotsk Sea Water, where surface chlorophyll a concentrations
was the highest but not related to the zooplankton biomass at 3-km scale. In contrast, thedensity of auklets was high in the coastal Soya Warm Current Water, where acousticallydetermined fish biomass was large, and showed positive relationship with the fishbiomass in the surface layer. This species-specific difference in the responses to preydensity might be related to prey-searching behavior i.e., Rhinoceros Auklets possibly
search prey under water visually, but Short-tailed Shearwater may search using olfactory
cue from phytoplankton to locate zooplankton patches in the surface.

34

Influence of physical oceanographic condition totransportation of diatom and silicoflagellate particles in thesouthwestern Canada Basin
Jonaotaro Onodera, Eiji Watanabe, Satoshi Kimura, Naomi Harada
Institute of Arctic Climate and Environment Research, Japan Agency for Marine-Earth
Science and Technology, 2-15 Natsushima-cho, Yokosuka, 237-0061, Japan
In order to monitor the lower-trophic marine ecosystems in changing Arctic Ocean, we
have studied the relationship between physical oceanographic condition and settlingparticle fluxes of diatom and silicoflagellate. Sediment trap samples were collected off
the north of Barrow Canyon (NBC) and the northern part of Hanna Canyon (NHC) fromfall 2015 to summer 2017. Diatom settling flux increased in summer as a reflection ofseasonal productivity increase. The assemblages of settling diatoms at NBC wascharacterized by relative dominance of Thalassionema nitzschioides, which is sometimes
observed in southwestern Canada Basin water, for the first deployment period, and seaice related species such as Fossula arctica for the second deployment period. The relative
abundance of sea-ice related species was higher at NHC, probably because of the mooring
position in more nutrient-rich condition compared to that at NBC. At NBC, diatom andsilicoflagellate settling-fluxes also increased with particulate organic carbon in early
winter 2016/2017. This reflected the temporal lateral advection of Pacific-origin watersfrom shelf to basin as the result of temporal changes in atmospheric and physicaloceanographic condition. The settlement of biogenic particles from shelf to basin in
addition to vertical settlement of in situ biogenic particles may affect the ecosystems fordeeper water mass and sea floor in the southwestern Canada Basin.

35

Optimization of salmon release operation under changing
climate in the Okhotsk coast, Japan
Sei-Ichi Saitoh 1,2,4, Yasuyuki Miyakoshi 3, Fumihiro Takahashi 4, Takafumi Hirata 1,
Masahide Kaeriyama 1, Irene D. Alabia 1, Takashi Hosokawa 5, Tatsuya Miyoshi 2,6 andNariaki Sakamoto7
1

Arctic Research Center, Hokkaido University
2
NPO Digital Hokkaido Community
3
Kitami salmon Enhancement Program association
4
Green & Life Innovation, Inc.
5
Nitto Seimo Co., Ltd.
6
Docon, Co., Ltd.
7
Meteorological Research Institute, Japan Meteorological Agency
Chum salmon is one of important fishery resources in the North Pacific. Recently, underchanging climate, return of chum salmon in Hokkaido tend to decrease. More precise
juvenile release operation is required for adapting to changing climate including
warming sea temperature with adjusting sea entry condition. It is necessary for this
precise operation to predict coastal marine environment in the release period andmonitor short-term change in coastal residency. We develop a supporting information
system for optimization of salmon release operation in Okhotsk coast. This system wasdesigned as web-based visualization to consist two service sites, monitoring of marine
environment (marine site) and supporting of salmon release operation (release site). In
marine site, we employ the output of eddy-resolving analysis model based on fourdimensional variational assimilation and a high(2-km) resolution forecast model
covering Japanese coastal areas developed by Japan Meteorological Agency. We alsouse GCOM-C satellite SGLI data, sea surface temperature (SST) and chlorophyll-a,with 250m spatial resolution operated by JAXA. In release site, there are two functions,
one is SST prediction function and the other is salmon release simulation function. In
SST prediction page, we obtain three months prediction SST using autoregressivemodel developed by using long term over 20 years Satellite SST data sets with R
package. In salmon release simulation page, when we input number of release
operation, date, release fork length, and number of release salmon, we obtain mean fork
length, which is one of index of survival/return rate, in the period of offshoring fromcoastal residency. This is a kind of release navigation tools. We will start to use theprototype system this salmon release season in spring 2021.

36

Identifying ecosystem reference states with “Chance andNecessity” model simulations
Eliot Sivel
Institute of Marine Research

The Barents Sea is a subarctic shelf sea in which fisheries are important. During the last five
decades, variations of environmental drivers and fisheries contributed to important variationsof many ecological components of the Barents Sea ecosystem. Understanding the effect ofvariation in external drivers on the ecosystem are essential to predict its future dynamics.
Comparing observed past ecosystem states and variability with a reference, is one way to better
understand the effect of external drivers on the ecosystem. One challenge is then to define thereference for ecosystem states and variability. This can be achieved by simulating ecosystem
dynamics. In this study, we use “Chance and Necessity” modelling to simulate the reference
variability of the Barents Sea ecosystem. The model simulates trophic interactions within asimplified food-web from plankton to whales. The prey-predator interactions are random but
constrained by biological and ecological principles. We compare observed recent ecosystem
states and variability to reference simulations. Our results show that the states of the Barents
Sea ecosystem during the last three decades, which are characterized by high biomass of
demersal fish and low biomass of marine mammals, only covers a fraction of the possiblereference states. In addition, we find that inter-decadal fluctuations between top-down andbottom-up trophic control are expected features of the Barents Sea ecosystem.

37

Stratification in the northern Bering Sea in early summer of2017 and 2018
Hiromichi Ueno, Mizuki Komatsu, Zhaoqianyi Ji, Ryo Dobashi, Miaki Muramatsu,
Hiroto Abe, Keiri Imai, Atushi Ooki and Toru Hirawake

We investigated spatial and interannual variation in the physical environment in thenorthern Bering Sea focusing on stratification, which is one factor affecting biologicalproduction in Arctic/subarctic regions. In particular, we analyzed in situ data obtained
onboard the training ship Oshoro Maru in early summer in 2017 and 2018. We found thatstratification in the areas just north of St. Lawrence Island (around 64.5°N and west of
168.5°W) and south/southwest of St. Lawrence Island was significantly weaker in 2018
than in 2017. These results are consistent with the extremely low sea-ice extent present
in the winter of 2017/2018, which would have resulted in less freshwater being supplied
to the surface layers and a warmer and less saline bottom water. Conversely, stratification
was as strong in 2018 as in 2017 in the area close to the Alaska mainland, including theBering Strait area, suggesting that the Alaskan Coastal Water dominates stratification inthis area in early summer. Moreover, we found that the weakly stratified water column inthe Bering Strait area stratified quickly shortly after the occurrence of strong northerly
winds, likely because of the Ekman transport of warm and low-salinity Alaskan Coastal
Water from the east.

38

Distribution of Pu-239 and Pu-240 in the Eastern Chinese
seas and its implications in the qualification of oceanicderived species
Jinlong Wang
State Key Laboratory of Estuarine and Coastal Research, East China Normal
University, Shanghai 200241, P. R. China
Concentrations and isotopic composition of plutonium (Pu) are widely used for its
source identification and to determine transport processes of Pu-associated particulatematter and water. We investigated the concentrations of 239Pu and 240Pu and their ratios
in a number of sediment samples from the Eastern Chinese seas (i.e., Bohai Sea (BS),Yellow Sea (YS) and East China Sea (ECS)). The 239+240Pu activity concentrations insurface sediment samples were found to range between 0.001 and 0.288, between 0.014
to 0.659 between 0.048 and 0.492 Bq kg-1 in the BS, YS and ECS surface sediments,
respectively; the 240Pu/239Pu atom ratios ranged from 0.173 to 0.256, from 0.18 to 0.31
and from 0.158 to 0.297 in the BS, YS and ECS surface sediments, respectively, andwere mostly higher than the mean global fallout value of 0.18 and lower than the Pacific
Proving Ground (PPG) value of 0.36. These observations clearly indicate a signal of
PPG close-in fallout Pu input to the Eastern Chinese seas. From the mass balance, 41%
239+240

Pu (8.9×109 Bq yr-1) and 18% 210Pb (2.4×1012 Bq yr-1) in the NYS weretransported from the Southern Yellow Sea. The PPG input appears to be the dominantsource of Pu to the ECS, accounting for 45%-52% of the total inventory. Using Pu as a
tracer, we can estimate that the oceanic 210Pb input into the ECS to be (1.7 −2.0) × 1015
Bq. In the BS, 63% 210Pb was from atmospheric deposition and 84% 239+240Pu wascontributed by riverine input. It is estimated that (1.8-2.6)×108 ton y-1 and (3.6-3.8)×108
ton y-1 sedimentary particles could be transport from the BS to NYS and from the NYS
to Southern Yellow Sea by using the export flux of 239+240Pu and 210Pbex, respectively.
Using Pu as a tracer, we estimated that the oceanic input contributed 2.0 tons y-1 Hg and
1.0 ×103 tons y-1 Zn to the SYS sediments during 2014, which accounts for 33% and 3%of total buried Hg and Zn, respectively. Our study shows that the 240Pu/239Pu atom ratio
is useful not only to obtain a better insight of the biogeochemistry influenced by theKC, but also to trace the long-range transport of other particle-reactive species.

39Arctic marine biogeochemical modeling in the ArCSII Project
Eiji Watanabe
1Japan Agency for Marine-Earth Science and Technology, Yokosuka, Kanagawa, Japan

The Arctic Challenge for Sustainability II (ArCS II) is a national flagship project
operated from June 2020 to March 2025 and fosters various Arctic researches. In theocean research program, a couple of pan-Arctic sea ice‒ocean modeling studies are
conducted with different experimental designs (e.g., horizontal resolution andintegration period) following previous works [Park et al., 2020, Science Advances;
Watanabe et al., 2019, JGR Oceans; Watanabe et al., 2017, DSR-I]. In this meeting,three topics will be briefly presented. First, we evaluate sensitivity of ocean
acidification to riverine inputs of biogeochemical variables (nitrate, silicate, dissolved
inorganic carbon, and total alkalinity). Numerous decadal experiments for 1979–2018
were performed using the 25-km grid version. The simulation results indicated thatthose riverine inputs slowed down ocean acidification in the many Arctic regions.
Second, we participate in the Ice Algae Model Intercomparison Project Phase 2(IAMIP2). In the Phase 1, seasonal, interannual, and decadal variations in the Arctic
ice-algal productivity for 1980–2009 were compared under the Forum for Arctic
Modeling and Observational Synthesis (FAMOS) framework. In the Phase 2, theexperiment period will be extended to 150 years spanning from the mid-twentiethcentury to the end of the twenty-first century, using the same atmospheric forcing
dataset based on outputs from the Coupled Model Intercomparison Project phase 6(CMIP6). Third, transport processes of seafloor sediments from the Chukchi shelf to thewestern Arctic basin are investigated in collaboration with sediment trap measurements
at four sites: Chukchi Abyssal Plain (CAP), Northwind Abyssal Plain (NAP), North of
Hanna Canyon (NHC), and North of Barrow Canyon (NBC). We performed interannual
experiments for 2001–2019 using the 5-km grid version which newly incorporated theresuspended particles (RP) and found that mesoscale eddies and the westward Chukchi
Slope Current played an important role in the RP transport.

40

Foraging behavior and prey field of Short-tailed Shearwaters
using northern North Pacific and Southern Ocean
Yutaka Watanuki1, Nodoka Yamada1, Sarara Azumi1, Hiroto Murase2, Koki Abe3,
Bungo Nishizawa1,5*, Haruka Hayashi3, Takashi Yamamoto4, Tohru Mukai1
1School of Fisheries Sciences, Hokkaido University
Tokyo University of Marine Science and Technology
3
Fisheries Resources Institute4
Meiji University
5
National Institute of Polar Research, *JSPS Research Fellowship for Young Scientist
2

A number of seabird species make long (~10,000km) latitudinal migration andindividuals from each colony often use the separate non-breeding regions repeatedly for
their life. Ecological reasons of this migration have long been explored. Geographicaldifference in the seasonality of marine primary production is hypothesized to be a
driving factor. Comparison of prey field and foraging activity between non-breeding
and breeding regions will give additional clue. Short-tailed Shearwaters (Ardennatenuirostris) breed in Tasmania in October – April and feed mainly in Indian Sector ofSouthern Ocean (ISO). During the non-breeding period (June – September) they used
the south-eastern Bering Sea (BES), the south Okhotsk Sea (OHS), and southern
Chukchi Sea (CKS). We investigated their foraging activity using geolocators, the preycharacteristics using stable isotope value of their feathers and blood, and theirrelationships with the prey density using boat census and acoustics. Bird using OHS fed
on prey of lower trophic level than those using BES during non-breeding, while thoseusing ISO fed on more higher trophic during breeding. Birds showed more intense
foraging activity (greater number of shorter foraging bouts, lower proportional on-water
time, and longer daily moving distance) in ISO than others, and in CKS than BES and
OHS. At sea density of birds was in the order as OHS>BES>ISO, while density of prey
(zooplankton) in surface layer was BES>ISO>OHS. Birds tended to forage in the places
where prey density was high and the association at 5-10 km bin size was stronger in
OHS and ISO than BES. High energy requirements and limitation of at sea time during
breeding and high energy requirements before migration may request intensive foraging
in ISO and CKS, respectively. Geographical differences in marine environment also
might affect relationships between prey field and foraging activity.

41Comparison of population structure, vertical distribution, andgrowth of the sympatric, carnivorous, mesopelagic copepods
Paraeuchaeta glacialis and Heterorhabdus norvegicus in thewestern Arctic Ocean: Occurrence of r-strategy mesopelagic
copepods may be related to their specialized feeding mode
Atsushi Yamaguchi1,2, Carin J. Ashjian3, Robert G. Campbell4
1
Graduate School of Fisheries Sciences, Hokkaido University, 3-1-1 Minato-cho, Hakodate, Hokkaido, 041-8611,
Japan
2
Arctic Research Center, Hokkaido University, Kita-21 Nishi-11 Kita-ku, Sapporo, Hokkaido, 001-0021, Japan
3
Biology Department, Woods Hole Oceanographic Institution, 266 Woods Hole Rd., Woods Hole, Massachusetts,
02543, USA
4
Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island, 02882, USA

Life cycles of copepods in the Arctic Ocean primarily have been studied for epipelagic
omnivorous copepods and little information is available for mesopelagic carnivorous
species. Here the life cycles of two mesopelagic carnivorous copepods (Paraeuchaeta
glacialis and Heterorhabdus norvegicus) are described. For both, reproductions
occurred between January and March, corresponding with the seasonal peak in prey
abundance. Vertical distributions and inter-molt growth varied with species. Early
copepodite stages and adult males of P. glacialis, which produces a small number oflarge eggs (K-selection), were distributed in deeper layers while late copepodite stages
and adult females were in shallower layers. Since the inter-molt growth of the stages
in the deeper layers was small, their growth was slow, resulting in a two-year generation
time. In contrast, all life stages of H. norvegicus, which produce many small-sized eggs
(r-selection), were distributed at the same depth layer but showed constant, large intermolt growth across all stages. The faster growth of each copepodite stage may allow
them to have a one-year generation time. To achieve faster growth of H. norvagicus in
the food-limited mesopelagic layer, a specialized feeding mode (incorporating avenomous injection spine and large beak) may have an important function.

42

Distribution and shell condition of Limacina helicina inaragonite undersaturated waters of the Canada Basin
1

Michiyo Yamamoto-Kawai, 1Masataka Seo, and 2Katunori Kimoto

1

Tokyo University of Marine Science and Technology
2
Japan Agency for Marine-Earth Science and Technology
Aragonite undersaturation has been observed in the surface and subsurface layers of theCanada Basin for more than a decade. In this study, we have investigated distribution ofshelled pteropod, Limacina helicina, in the Canada Basin in September of 2019. Samples
were collected using a closing NORPAC net, from 0-50 m, 50-100 m and 100-200 m
layers. Juveniles of L. helicina were most abundant in the top 50 m layer but were less inthe central Basin, where aragonite undersaturation were observed. The abundance of L.
helicina positively correlated with both aragonite saturation state and chlorophyll aconcentration. Shell density, measured by using a MXCT (Microfocus X-lay Computer
Tomography), did not show clear relationship with environmental factors. Most of
individuals found in aragonite undersaturated water had undamaged shells. This confirmsthat periostracum protects their shells from dissolution. Nevertheless, we also foundsamples with sever dissolution. These results suggest that although L. helicina is protectedby periostracum, a scratch can now lead to sever shell dissolution.

43

Arctic Ocean CO2 uptake
S. Yasunaka1*, A. Olsen2, M. Manizza3, D. Carroll4, P. Landschützer5, E. Watanabe1
1

2

JAMSTEC, Japan
University of Bergen and Bjerknes Centre for Climate Research, Norway
3
Scripps Institution of Oceanography, U.S.A.
4
Moss Landing Marine Laboratories, U.S.A.
5
Max Planck Institute for Meteorology, Germany

We updated the estimates of the air–sea CO2 flux in the Arctic to December 2017, andnow obtained 252 monthly maps of the CO2 flux in the Arctic Ocean and its adjacent seas.
This was done by mapping partial pressure of CO2 in the surface water (pCO2w) using aself-organizing map (SOM) technique incorporating chlorophyll-a concentration (Chl-a), sea
surface temperature, sea surface salinity, sea ice concentration, atmospheric CO2 mixing ratio,
and geographical position. The pCO2w data were obtained by shipboard underway
measurements or calculated from alkalinity and total inorganic carbon of surface water
samples. Subsequently, we investigated the basin-wide distribution and seasonal tointerannual variability of the CO2 fluxes. The estimated annual CO2 uptake by the Arctic
Ocean was 160 ± 130 TgC yr–1. The CO2 influx was strongest in winter in theGreenland/Norwegian Seas (> 10 mmol m–2 day–1) and the Barents Sea (> 12 mmol m–2 day–1
) because of strong winds, and strongest in autumn in the Chukchi Sea (> 7 mmol m–2 day–1)
because of the sea-ice retreat. In recent years, the CO2 uptake has increased in theGreenland/Norwegian Sea and decreased in the southern Barents Sea, owing to increased anddecreased air–sea pCO2 differences, respectively.
We also compared our results to other mapping and model results; ETH_SOM-FFN,
ECCO2Darwin, ECCO_Darwin_V4, and Arctic_NEMURO-C. Large CO2 uptakes arecommonly shown in the Norwegian Sea, the Greenland Sea and the Barents Sea in all seasons,and in the Chukchi Sea in autumn. In several results, the Arctic Ocean CO2 uptake tends tostrengthen in recent years in association with the sea ice retreat, while air–sea pCO2
differences seems to weaken after 2007 due to the rising of the surface temperature.
2[mmol/m /day]OSOM+ ETH_SOM-FFN

x Arvtic_NEMURO-C△ECCO2Darwin● ECCO_Darwin_V4

Figure 1. Air-sea CO2 flux in the Chukchi Sea

References[1] S. Yasunaka et al., Arctic Ocean CO2 uptake: an improved multi-year estimate of the
air-sea CO2 flux incorporating chlorophyll-a concentrations, Biogeosciences 15 (2018)44

International Convention and Prevention of Marine Pollution: Heavy Metal
Concentration in the Bay of Bengal
Abu Hena Muhammad Yousuf1,2*Abstract
International convention on marine pollution provided less attention for the protection of themarine environment and of the high seas beyond coastal areas. The Stockholm Declaration on
the Human Environment determined the concern regarding the whole marine environment, andemphatic reflection was done in the provisions of the Law of the Sea Convention. Eight heavy
metals were analysed from both water and sediment samples of the Bay of Bengal (BoB). The
decreasing trend of metals were observed in water samples: Zn (0.91±8.11) > Ni (0.78±0.72)> Cr (0.56±0.18) > Cu (0.16±0.24) > Pb (1.32±0.21) > As (1.14±0.95) > Hg (1.00±0.04) >Cd (0.07±0.03)μg/L and in sediment samples: Zn (46.53±23.57) > Cr (22.58±7.81) > Ni
(21.17±12.17) > Pb (14.64±6.65) > Cu (13.04±8.19) > As (4.06±1.62) > Hg (0.03±0.02) >Cd (0.02±0.01)mg/kg. For the sustainability of the marine resources, the integration of
Ecosystem Based Management and Marine Spatial Planning (EBM-MSP) provides a platform
for different levels of governing bodies and stakeholders for the transparent, smooth andprogressive decision-making process, that enables monitoring and surveillance in order tomanage with future uncertain conditions.
Keywords: Marine pollution; Heavy metal; Bay of Bengal; Ecosystem Based Management;
Marine Spatial Planning.

* Corresponding author: yousuf.ocn@du.ac.bd; yousuf.ocn@westernsydney.edu.au
1
Department of Oceanography, Faculty of Earth & Environmental Sciences, University of Dhaka.
2International Centre for Ocean Governance (ICOG), School of Law, Western Sydney University,
Victoria Rd, Rydalmere NSW 2116, Australia.

45Impacts of Riverine Carbon and Nutrient Delivery on Arctic Ocean Acidification○Yuanxin ZHANG1・Michiyo YAMAMOTO-KAWAI2・Eiji WATANABE3(1Tokyo University of Marine Science and Technology・Graduate School of Marine Science and Technology)(2Tokyo University of Marine Science and Technology・Department of Ocean Sciences)(3Japan Agency for Marine-Earth Science and Technology・Institute of Arctic Climate and Environment Research)

KEY WORDS: Ocean Acidification・Arctic Ocean・Model Simulation・Riverine Fluxes

1.

Introduction
Rapid environmental changes are happening in the Arctic Ocean, such as extensive sea ice retreat, seawater warming,

ocean acidification (OA). Effect of climate change on land also affects the Arctic Ocean by increasing riverine
biogeochemical delivery (carbon and nutrient) via runoff increase, permafrost thaw, and tree-line advance[1]. Changes inriverine delivery of carbon and nutrient may affect the primary production, air-sea CO2 fluxes, and OA significantly. It
was revealed that aragonite undersaturation (caused by OA) has been observed for more than one decade since 2006 in
the surface waters of Arctic Ocean[2]. However, it is still unclear that to what extent the delivery of riverine
biogeochemical fluxes (R_BGC) has an impact on OA, as well on primary production and marine ecosystem in the Arctic
Ocean.
2.

Data & Method
By using a Pan-Arctic Sea Ice-Ocean Model (COCO) coupled to an Arctic and North Pacific Model for Lower-

trophic Marine Ecosystem with Carbonate Chemistry (Arctic NEMURO-C), we conducted sensitivity experiments tounderstand the impact of riverine biogeochemical delivery on OA (including indexes of pH, aragonite saturation state:ΩAr) in several Arctic sub-regions for 1979-2018. Four experiments are composed of 1. Without R_BGC, 2. With only
R_Carbon (Riverine TA and DIC fluxes), 3. With only R_Nut (Riverine Nitrate and Silicate fluxes), 4. With R_BGC.
Monthly climatological riverine carbon and nutrient data were obtained from the Arctic Great Rivers Observatory(ArcticGRO). Monthly climatological freshwater fluxes known as R-ArcticNET were obtained from the Arctic Ocean
Model Inter-comparison Project (AOMIP).
3.

Results & Discussion
Compared with result from in the case 1 (Without R_BGC case: only riverine freshwater fluxes were involved), it isfound that R_BGC increases pH and Ω Ar in waters shallower than ~100 m in almost the whole Arctic Ocean. In surface
waters of the central Arctic (latitude > 83°N), mean increments during 1989-2018 of pH and ΩAr by R_BGC are ~0.01
and ~0.06, respectively, which is mostly due to delivery of R_Carbon in this region where the effect of R_Nut delivery
is negligible.
Higher pH and ΩAr affected by R_BGC are shown in surface waters near the coastal regions, where large rivers enter
into the Arctic Ocean, as well as along the Lomonosov Ridge, which reflects the distribution pattern of transpolar driftthat transports river waters further into the central Arctic. The largest increments of pH and ΩAr by R_BGC are found in
the surface waters of Laptev Sea and Kara Sea where simulation with R_BGC causes a higher pH by ~0.1 and higher Ω Ar
by ~0.1. In these seas, delivery of R_Nut attributes up to ~20% of pH increment and ~10% of Ω Ar increment, which is aconsequence of enhanced primary productivity by the riverine nutrient supply.
References:[1] Terhaar et al., (2019). Global Biogeochemical Cycles, 33, 1048–1070.

45[2] Zhang, Y. et al., (2020). Geophysical Research Letters, 47, e60119.